DHC1 Chipmunk

Initially formed as a subsidiary of the de Havilland Aircraft Company on March 5, 1928, de Havilland Canada produced many of its parent company's aircraft before producing their first indigenous aircraft, the DHC-1 Chipmunk. Designed by Wsiewolod Jan Jakimiuk, the former chief designer of the Polish aircraft manufacturer PZL "Warszawa-Okecie" S.A, it was developed as a replacement for the venerable de Havilland DH82A Tiger Moth. The prototype (CF-DIO-X) flew for the first time at Downsview, Toronto on May 22, 1946 and despite the crash of the second prototype on January 19, 1947 after failing to recover from a spin, deliveries of production aircraft to the Royal Canadian Air Force commenced in 1948. According to some sources, the aircraft was originally nicknamed the "Jakimiuk" after its designer but was renamed the Chipmunk when Phillip Garratt (the manager of de Havilland Canada) returned from a vacation during which he had been "entertained" by the antics of several chipmunks. Even though the name Jakimiuk was popular, Chipmunk had a certain similarity so the name was adopted. This led to the decision to name all subsequent de Havilland Canada aircraft after Canadian animals, whether this is fact or an urban legend is unclear.

The design of the Chipmunk took advantage of several wartime advances in aviation construction, resulting in an aircraft that differed from many previous de Havilland offerings. The most noticeable was the change from the trusted wood and steel tube to all metal construction. Fabric covering was still used on areas such as the wings aft of the main wing spar, the trailing edge flaps and the control surfaces; however, the wing leading edge and fuselage were of stressed-skin, metal construction. The instructor and student were seated in a tandem cockpit that was covered by a rearward sliding, one-piece Plexiglas canopy. Considering the bitter winters that could be encountered in Canada, this was a welcome change from older open-cockpit designs. Two areas of the Chipmunk's design that remained true to traditional de Havilland ways were the shape of the vertical stabiliser and rudder and the use of a 142 hp de Havilland Gipsy Major 1C engine driving a fixed pitch, two-blade propeller. Although the choice of an engine of somewhat modest horsepower could be seen by some as "typically British" when compared to the powerplants in use in some contemporary American aircraft, the Chipmunk's MAUW (Maximum All Up Weight) of around 1,800 lbs gave it an excellent power to weight ratio.

The first production Chipmunks were given the designation DHC-1 and entered service with the RCAF as the Chipmunk T.1. A change to the 145 hp Gipsy Major 10 engine resulted in the DHC-1A-1 and then the fully aerobatic, Gipsy Major 1C powered DHC-1B-1 (the previous models being only partially aerobatic). Further minor improvements, design and engine changes and variants produced for export led to a host of suffixes, ending with the 142 hp Gipsy Major 1G powered DHC-1B-2-S5. The Royal Air Force also expressed an interest in the Chipmunk and, following evaluation of two aircraft by the Aeroplane and Armament Experimental Establishment at Boscombe Down in England, it was ordered into production for the RAF under Air Ministry Specification 8/48 as a fully aerobatic, ab initio trainer. The de Havilland parent company began building Chipmunks as the T.10 for the RAF and subsequently, some of these aircraft were passed to the Army and later to the Royal Navy. Although at first glance it was visually similar to the Canadian aircraft, apart from a multi-panel cockpit canopy instead of a one-piece version, there were many subtle differences. These included (to name a few) being built to imperial measurements as opposed to metric, the installation of a 145 hp Gipsy Major 8 engine, faired landing gear legs, different wingtips and cockpit layout, a slightly thinner aluminium skin and changes to the attachments for the wings and tailplane and elevator profile.

Deliveries of the T.10 began in February 1950 with the Oxford University Air Squadron being the first to receive the type. This was soon followed by deliveries to 19 RAF Reserve flying schools and two Rhodesian Air Training Group schools. Eventually, the aircraft went on to replace the DH82A Tiger Moth with all 17 university air squadrons in England as well as the RAF Volunteer Reserve flying schools and, from time to time, the RAF College at Cramwell.

As with several previous de Havilland aircraft, the Chipmunk was to have royal connections in Britain. A brand new T.10 was delivered to RAF White Waltham and used to teach HRH Prince Philip, the Duke of Edinburgh, to fly. Trained by Flight Lieutenant Caryl Gordon, the Duke made his first solo on December 20, 1952. Sixteen years later, HRH Prince Charles, the Prince of Wales, was also being taught to fly in a Chipmunk. On July 30, 1968, the Prince began his initial flights in a T.10 at RAF Tangmere before more formal training began on October 28 of the same year. After fourteen and a half hours of instruction by Squadron Leader Philip Pinney, he made his first solo flight at RAF Bassingbourn on January 14, 1969.

Even though the DHC-1 was originally designed and built in Canada, only 217 of the eventual 1,291 Chipmunks produced came from that country. The vast majority were produced in England with 1,000 rolling off the de Havilland production lines before production ended in 1958. Out of this total, 735 went mainly to the RAF as the T.10 and the T.20 export version with civilian models being built as the Mk.21. As well as the Canadian and British aircraft, a further 60 Chipmunks were produced under licence in Portugal by Indústria Aeronáutica de Portugal, SA (OGMA). By the late 1950s many ex-RAF T.10s were being released into the civil market as the Chipmunk Mk.22 while a number of those that remained in service had larger fuel tanks installed and were re-designated the Chipmunk Mk.22A. Further after-market conversions included the heavily modified Mk.23 crop sprayer with a hopper in place of the front cockpit developed in England by Farm Aviation Services. Another agricultural version was also produced as a joint venture by Sasin Aircraft Services and Aerostructures in Australia as the SA29 Spraymaster. Although similar in concept to the Mk.23, the SA29 was very different structurally, had a one-piece canopy with a cable cutter, streamlined strakes and a dorsal fin fillet. It also had wing endplates and different spray bars. The same company also produced the Sundowner, a modified Chipmunk with a 180 hp Lycoming O-360 engine.

With their excellent handling characteristics, it came as no surprise that a number of surplus Chipmunks were converted for use in aerobatic competitions and displays. The Super Chipmunk was one such conversion that went on to win the American national aerobatics championships in 1969. Work on this aircraft began in 1967 when Jean Paul Huneault of Pierrefonds, Quebec started modifying an ex-RCAF DHC-1B-2-S3. The original Gipsy Major engine was replaced by a 210 hp Continental IO-360-C6A driving a Hartzell constant-speed propeller and the control surfaces were re-skinned in metal. The airframe remained basically original although new engine mounts and a revised cowling were fitted as well as shortened landing gear and electrically driven flaps. An updated Super Chipmunk powered by an aerobatic version of the 210 hp Teledyne Continental IO-360-HB (as used in the CT/4B Airtrainer) is still available in kit form today.

Another far more modified version was the late Art Scholl's DHC-1A "Pennzoil Special" that performed at air shows throughout America in the 1970s and early 1980s. Although it also started life as a surplus RCAF Chipmunk, by the time it had been rebuilt it was a totally different aircraft. A much more powerful 260 hp six cylinder Lycoming GO-435 engine was installed, the tandem cockpit was changed to a single seat one, retractable landing gear was fitted, the wingspan was reduced by 3 ft, 4 in and the area of the vertical stabiliser and rudder was increased by a quarter. In addition, the wingtips, tailplane and rudder lost their distinctive de Havilland curves and acquired a more "squared off" look. This aircraft still exists and is on display at the Smithsonian Institution's National Air and Space Museum in the United States.

Not only did the Chipmunk prove to be very popular worldwide (allegedly seeing service in over 60 countries) but it also had amazing longevity. In Canada, the aircraft was finally retired from service in 1971 while those in the RAF were gradually replaced by the BAe (Scottish Aviation Bulldog) T1 but still continued training pilots until 1997. As well as being used as a trainer, some countries employed the Chipmunk in roles as diverse as glider towing, artillery observation posts and even on military security patrols. As mentioned previously, the aircraft had excellent handling characteristics which, when combined with its beautifully harmonised controls, has led to the Chipmunk being described as "just like a Spitfire to fly but with a lot less power". The current use of a T.10 to train Spitfire pilots for the RAF's Battle of Britain Memorial Flight is perhaps a testimony to this. Of the estimated 500 Chipmunks still in existence, the vast majority are still airworthy and in private ownership, including here in New Zealand. Even though the Royal New Zealand Air Force never used any variants of the DHC-1, it has proved popular with private owners and a number have been imported into the country since the 1990s.